{
\def\sym#1{\ifmmode^{#1}\else\(^{#1}\)\fi}
\begin{tabular*}{\hsize}{@{\hskip\tabcolsep\extracolsep\fill}l*{6}{c}}
\toprule
                           &\multicolumn{2}{c}{Democratic Vote}          &\multicolumn{2}{c}{Republican Vote}          &\multicolumn{2}{c}{Incumbent Vote}           \\\cmidrule(lr){2-3}\cmidrule(lr){4-5}\cmidrule(lr){6-7}
                           &\multicolumn{1}{c}{Model}&\multicolumn{1}{c}{Model}&\multicolumn{1}{c}{Model}&\multicolumn{1}{c}{Model}&\multicolumn{1}{c}{Model}&\multicolumn{1}{c}{Model}\\
\midrule
\emph{IV: Mean wind potential * National wind capacity}&                      &                      &                      &                      &                      &                      \\
Cumulative capacity (MW)   &        0.032\sym{**} &                      &       -0.032\sym{**} &                      &        0.007         &                      \\
                           &      (0.013)         &                      &      (0.013)         &                      &      (0.013)         &                      \\
Cumulative count           &                      &        0.052\sym{**} &                      &       -0.052\sym{**} &                      &        0.011         \\
                           &                      &      (0.021)         &                      &      (0.021)         &                      &      (0.021)         \\
\midrule
Observations               &         1143         &         1143         &         1143         &         1143         &         1038         &         1038         \\
States                     &          287         &          287         &          287         &          287         &          285         &          285         \\
\(R^{2}\)                  &         0.88         &         0.88         &         0.88         &         0.88         &         0.73         &         0.73         \\
\bottomrule
\multicolumn{7}{l}{\footnotesize \sym{*} \(p<0.10\), \sym{**} \(p<0.05\), \sym{***} \(p<0.01\)}\\
\end{tabular*}
}
